Sigma Noise Comparison: Not Fair part 2

Started Nov 27, 2002 | Discussions thread
OP tom jacobson Contributing Member • Posts: 516
Re: Sigma Noise Comparison: Not Fair part 2


Kok Chen wrote:

tom jacobson wrote:

I don't think I am getting my point across! Sorry for that. What
I am talking about is the size of the noise chunks. The SD-9 noise
appears to be fine little chunks, and the D60 appears to have
larger chunks of noise.

That is precisely what I was addressing, Tom.

What you refer to as "larger chunks" are simply noise that have a
lower spatial frequency structure.

If you add all the "area" of the noise and compare to the area of
the rest of the image, that is a kind of crude "signal-to-noise"
ratio. This ratio does not change when you scale an image up.

However, the noise will be low-passed (or, as you say, in big
chunks) and that, is noise that is more "pink." Again, it is not
the color of the noise that is pink, the "pink" refers to lower
spatial frequencies. And the human visual system does not like
"pink noise."

Call it "small random grain" vs "clumpy noise," if you like.

  • kc

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